SUMOylation is essential for sex-specific assembly and function of the <i>Caenorhabditis elegans</i> dosage compensation complex on X chromosomes

Abstract

Significance Dosage compensation equalizes X-chromosome transcription between nematode males (1X) and hermaphrodites (2X) via a dosage compensation complex (DCC) that binds hermaphrodite X chromosomes to repress transcription by half. We show that several DCC subunits are modified by the small ubiquitin-like modifier SUMO in response to the signal that triggers DCC assembly onto X. DCC assembly and function require SUMOylation. DCC subunit DUMPY-28 also acts in condensin complexes essential for chromosome segregation, but its SUMOylation is DCC-specific. We propose that specific signals trigger DCC protein SUMOylation, stimulating robust complex formation. SUMOylation facilitates distinct activities of proteins that function in multiple complexes.